Single-particle entanglement gives rise to truly nonlocal effects like single-particle steering

TL;DR

This paper demonstrates that single-particle entanglement can produce genuine nonlocal effects like steering, challenging traditional views and opening new possibilities for quantum nonlocal tasks using wave function collapse and the Stern-Gerlach experiment.

Contribution

It shows how single-particle entanglement and wave function collapse can produce nonlocal steering effects, providing new insights into quantum nonlocality.

Findings

Single-particle entanglement enables nonlocal steering effects.

Wave function collapse can be exploited for nonlocal quantum tasks.

The nonlocality persists over large distances, confirming true nonlocal effects.

Abstract

In 1927, at the Solvay conference, Einstein posed a thought experiment with the primary intention of showing the incompleteness of quantum mechanics; to prove it, he uses the instantaneous nonlocal effects caused by the collapse of the wave function of a single particle -the spooky action at a distance-, when a measurement is done. This historical event precede the well-know Einstein-Podolsk-Rosen criticism over the incompleteness of quantum mechanics. Here, by using the Stern-Gerlach experiment (SGE), we demonstrate how the instantaneous nonlocal feature of the collapse of the wave function together with the single-particle entanglement can be used to produce the nonlocal effect of steering. In the steering process Bob gets a quantum state depending on which observable Alice decides to measure. To accomplish this, we fully exploit the spreading (over large distances) of the entangled wave function of the single-particle. In particular, we demonstrate that the nonlocality of the single-particle entanglement allows the particle to know which detector Alice is using to steer Bob's state. Therefore, notwithstanding strong counterarguments, we prove that the single-particle entanglement gives rise to truly nonlocal effects at two far a away places. This open the possibility of using the single-particle entanglement for implementing truly nonlocal task.